Solar eclipse of April 28, 1930

A total solar eclipse occurred at the Moon's ascending node of orbit on Monday, April 28, 1930, with a magnitude of 1.0003. It was a hybrid event, with only a fraction of its path as total, and longer sections at the start and end as an annular eclipse. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A hybrid solar eclipse is a rare type of solar eclipse that changes its appearance from annular to total and back as the Moon's shadow moves across the Earth's surface. Totality occurs between the annularity paths across the surface of the Earth, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. The Moon's apparent diameter was near the average diameter because it occurred 7.2 days after apogee (on April 21, 1930, at 13:50 UTC) and 6 days before perigee (on May 4, 1930, at 19:50 UTC).

Annularity was first visible in the eastern Pacific Ocean, then totality from California, Nevada, Oregon, Idaho and Montana, with annularity continuing northeast across the remainder of Montana and into central and eastern Canada and northern Labrador of the Dominion of Newfoundland (today's Newfoundland and Labrador in Canada). A partial eclipse was visible for parts of Hawaii, North America, and the northern Soviet Union.

Observations

During a hybrid solar eclipse, the apex of the Moon's umbral cone is very close to the Earth's surface, and the magnitude is very close to 1. The edges of the Moon and the Sun are very close to each other as seen from the Earth in both the total and annular portion of the path. A series of Baily's beads on the lunar limb provide an excellent opportunity to measure the size and shape of the Earth, as well as the mountains and valleys on the lunar limb. During this eclipse, scientists recorded the precise time of each phase of the eclipse in Camptonville, California. Because the duration of totality was just over one second, the photographic film needed to be inserted quickly after the start of totality. In addition, scientists recorded audio images with a long-wave receiver on an aircraft at the Mare Island Naval Shipyard. Each image had a time accurate to 1/5 second.

Prior to it, the hybrid solar eclipse of April 17, 1912, also belonging to Solar Saros 137, also occurred with a magnitude close to 1. Observations were made near Paris, France. Similar observations were also made during the annular solar eclipses of May 9, 1948 in Rebun Island, Japan and May 20, 1966 in Greece and Turkey, also belonging to the same solar Saros cycle.

Eclipse details

Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the Moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.

Eclipse season

This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.

Related eclipses

Eclipses in 1930

• A partial lunar eclipse on April 13.
• A hybrid solar eclipse on April 28.
• A partial lunar eclipse on October 7.
• A total solar eclipse on October 21.

Metonic

• Preceded by: Solar eclipse of July 9, 1926
• Followed by: Solar eclipse of February 14, 1934

Tzolkinex

• Preceded by: Solar eclipse of March 17, 1923
• Followed by: Solar eclipse of June 8, 1937

Half-Saros

• Preceded by: Lunar eclipse of April 22, 1921
• Followed by: Lunar eclipse of May 3, 1939

Tritos

• Preceded by: Solar eclipse of May 29, 1919
• Followed by: Solar eclipse of March 27, 1941

Solar Saros 137

• Preceded by: Solar eclipse of April 17, 1912
• Followed by: Solar eclipse of May 9, 1948

Inex

• Preceded by: Solar eclipse of May 18, 1901
• Followed by: Solar eclipse of April 8, 1959

Triad

• Preceded by: Solar eclipse of June 27, 1843
• Followed by: Solar eclipse of February 26, 2017

Solar eclipses of 1928–1931

This eclipse is a member of a semester series. An eclipse in a semester series of solar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.

The partial solar eclipse on June 17, 1928 occurs in the previous lunar year eclipse set, and the partial solar eclipse on September 12, 1931 occurs in the next lunar year eclipse set.

Saros 137

This eclipse is a part of Saros series 137, repeating every 18 years, 11 days, and containing 70 events. The series started with a partial solar eclipse on May 25, 1389. It contains total eclipses from August 20, 1533 through December 6, 1695; the first set of hybrid eclipses from December 17, 1713 through February 11, 1804; the first set of annular eclipses from February 21, 1822 through March 25, 1876; the second set of hybrid eclipses from April 6, 1894 through April 28, 1930; and the second set of annular eclipses from May 9, 1948 through April 13, 2507. The series ends at member 70 as a partial eclipse on June 28, 2633. Its eclipses are tabulated in three columns; every third eclipse in the same column is one exeligmos apart, so they all cast shadows over approximately the same parts of the Earth.

The longest duration of totality was produced by member 11 at 2 minutes, 55 seconds on September 10, 1569, and the longest duration of annularity will be produced by member 59 at 7 minutes, 5 seconds on February 28, 2435. All eclipses in this series occur at the Moon’s ascending node of orbit.

Metonic series

The metonic series repeats eclipses every 19 years (6939.69 days), lasting about 5 cycles. Eclipses occur in nearly the same calendar date. In addition, the octon subseries repeats 1/5 of that or every 3.8 years (1387.94 days). All eclipses in this table occur at the Moon's ascending node.

Tritos series

This eclipse is a part of a tritos cycle, repeating at alternating nodes every 135 synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee), but groupings of 3 tritos cycles (≈ 33 years minus 3 months) come close (≈ 434.044 anomalistic months), so eclipses are similar in these groupings.

Inex series

This eclipse is a part of the long period inex cycle, repeating at alternating nodes, every 358 synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee). However, groupings of 3 inex cycles (≈ 87 years minus 2 months) comes close (≈ 1,151.02 anomalistic months), so eclipses are similar in these groupings.

Notes

• Eclipse Predictions by Fred Espenak, NASA/GSFC
• The solar eclipse of April 28, 1930 Popular Astronomy, Vol. 38, p. 537, Makemson, Maud W.
• The Central Solar Eclipse of April 28, 1930 Journal of the Royal Astronomical Society of Canada, Vol. 24, p. 55